Colonoscopy Beats 'Camera Pill' at Catching Colon Cancer
WEDNESDAY July 15, 2009 -- Researchers had high hopes for a minimally invasive cancer-screening technique known as capsule endoscopy, but the "camera pill" appears to be less effective than standard colonoscopy at identifying precancerous polyps and cancer, new research from Belgium suggests.
Although able to identify many lesions and cancers, the relative underperformance of capsule endoscopy -- in which a patient swallows a tiny, battery-operated, excretable capsule fitted with a double-sided video camera -- suggests that for now the more invasive colonoscopy should remain the gold standard for colorectal cancer detection.
"Although this study shows encouraging results, the use of the colon capsule can not be recommended at this stage for colon screening," said study lead author Dr. Andre Van Gossum from the department of gastroenterology at Erasme University Hospital at the Free University of Brussels.
The findings were published in the July 16 issue of the New England Journal of Medicine.
The study involved more than 300 patients who were scheduled to undergo a colonoscopy at one of eight medical centers, because they either had a history of colon cancer (about one-third of the patients) or were suspected of having the disease (about two-thirds of the patients). The patients underwent capsule endoscopy and, after that, conventional colonoscopy.
Participants ranged in age from 22 to 84 (average age was nearly 59), and 55 percent were men.
The researchers determined that capsule endoscopy -- which does not require sedation -- is indeed a safe and less invasive technique for visualizing the colon.
Technically, the colon capsule functioned as intended in nearly 98 percent of patients, the team found. The pill was deemed easy-to-swallow, and none of the patients experienced any problems excreting the capsule. Nearly 93 percent did so within 10 hours of ingestion and before the pill's battery-life was exhausted. On average, travel time for capsule navigation through the full length of the gastrointestinal tract -- from mouth to anus -- was calculated at four hours.
Most side effects were observed as mild and passing, and related not to the pill ingestion itself but to the bowel-prep requirements. Described as more extensive than colonoscopy preps, this involves swallowing liquids designed to clean the colon and optimize pill movement and imaging.
The effectiveness of the colon capsule was directly related to how well the patients had cleaned their colons. Detection sensitivity was significantly worse among those patients with poor or fair colon cleanliness than those with good or excellent cleanliness.
Also, the pill procedure detected only 64 percent of polyps 6 millimeters in size or larger that were identified by standard colonoscopy. And with similarly sized advanced cancer, capsule screening captured just 73 percent of adenomas that were spotted by colonoscopy.
Of 19 confirmed cases of colon cancer uncovered through colonoscopies, just 14 were caught by the pill technique, the researchers noted.
The authors therefore concluded that capsule endoscopy is currently inferior to colonoscopy as a screening method, but they called for more research.
The noninvasive character of this technique has the potential to encourage more patients to get screened for colon cancer, Van Gossum said. In time, "technological improvements, as well as adapted protocol for colon preparation, could increase the sensitivity of this new method," he noted.
Dr. Felice Schnoll-Sussman, director of research with the Jay Monahan Center for Gastrointestinal Health at the New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City, said the capsule does have value, despite seemingly significant deficiencies in identifying both polyps and cancers.
"The results were still admirable in terms of what colon capsules were able to identify," she observed. "And although the prep for the capsule exam is more arduous than the prep for a colonoscopy, it seems that the experience was viewed as convenient, safe and tolerable."
"I think that in certain patient populations --those incapable of undergoing a colonoscopy because they are very difficult to sedate, or those that are just not willing to undergo a colonoscopy -- this may be an appropriate alternative," she said. "But patients will have to weigh the options, recognizing that the accuracy of colon capsule detection is lower."
For additional information and resources on capsule endoscopy, visit the American Society for Gastrointestinal Endoscopy.
Posted: July 2009
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